Holographic video display…..Credit: University of Arizona
A video screen that refreshes the image every two seconds doesn’t do wonders for motion or animation, but it’s a darned sight better than three minutes between refresh. That’s the progress made by Nasser Peyghambarian and Pierre-Alexandre Blanche at the College of Optical Sciences at the University of Arizona (Tucson, USA). Their first holographic image system, presented in 2008, though novel in displaying remote moving objects was obviously too slow (3 minutes!). The new system, described in the November 4, 2010 issue of Nature [Holographic three-dimensional telepresence using large-area photorefractive polymer] demonstrates a major improvement in the technology.
We’re talking about telepresence holograms, where the initial image is picked-up by cameras in one location, transmitted via broadband communications, and displayed in another location. The hologram is more or less three-dimensional, meaning that it gives the appearance of existing as a solid in space – you can look at it from various angles, including up and down, and the view of the object in the image changes accordingly.
“More or less” applies here, since as the picture above indicates the quality of the image isn’t very high and the screen refresh of 2 seconds isn’t fast enough for animation/motion. The image is improving, version to version, mainly because of advances in the ‘screen.’ A display unit for holograms is rather obviously different than one for a typical LCD television screen. For one thing, the 3-D image is created by a high powered but short burst of a laser onto specific elements called a hogel (holographic pixel – corresponding to the flat screen’s pixel).
This approach, one of several under development for holographic imaging, is quite different than the 3-D currently marketed for consumers. That kind of 3-D is based on projection of dual images and requires special glasses. Holographic images are (theoretically) much more lifelike – you can walk around them and view different sides – and no glasses are required.
The material used in the holographic screen is crucial, as it is for all kinds of screen displays. In this case the researchers chose a form of polymer (plastic) that has unusual light reflecting (photorefractive) properties. Continuous experimentation led to improving performance in the ability of the polymer to accept an image and then erase it for the next image. There is still a way to go, especially in the ability of the polymer to quickly change hogel states, the speed of the laser scan (which is now 50Hz, too slow), and the amount of power required for the laser.
Researchers in the field are looking at a roughly twenty year evolution for holographic technology before commercial prime-time. Eventually relatively simple/inexpensive camera systems, transmitted over very high bandwidth will produce full-color, full-motion video in ‘life-like’ three-dimensions. Just like we’ve seen in the movies (think Star Wars), only better. This is one of those technological advances that people can visualize already. Now all that has to happen is for the technology to catch up.